The present invention relates to a servo-actuated valve particularly suited for, although not limited to, use in automobile heating systems.
Heretofore, problems which individually and collectively have beset valves of this type, to various degrees, include: internal leakage preventing the valve from completely blocking fluid flow when closed especially at low fluid pressures and often caused by wear and foreign matter in the fluid; binding of the valve actuating mechanism and linkage preventing the valve from being smoothly and reliably actuated; the need for complicated manufacturing and assembly operations; relatively heavy weight often necessitating positive mounting to the vehicle by a separate mounting bracket; inability to consistently reliably operate over the temperature extremes to which subjected; poor sealing of the servo diaphragm to the servo actuator arm; and lack of strength in the servo housing when fabricated from inexpensive materials.
Accordingly, important objects of the present invention are to eliminate, or at least alleviate, the foregoing problems, including providing: two embodiments of a valve which is sufficiently lightweight that it can be hung directly in a heater hose line, an improved sealing arrangement for a valve in which resilient means continually biases the valve element into sealing engagement with the valve seat, which also uses the pressure of the input fluid to assist in sealing, which reliably closes even at very low fluid pressures, which in one alternative embodiment contains additional means to insure the proper operation of the valve at high pressures, and which is highly resistant to foreign matter and temperature variations; a valve which is relatively inexpensive and well-suited for mass production; an improved arrangement for interlocking the two halves of a vacuum servo housing which both strengthens the housing and seals the outer periphery of the servo diaphragm; a vacuum-tight seal for a servo diaphragm for preventing leakage around the connection of the servo actuator arm to the diaphragm; a simplified connection between the servo and the valve actuating member which requires no separate fastener, which minimizes backlash and any tendency to bind, which is easy to connect and which, once connected, cannot become disconnected during operation.
These and other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.